The present invention concerns insulated containers, more particularly self-contained insulated containers for maintaining an item at a predetermined temperature.
Insulated containers for storing perishable items such as foodstuff and medical specimens at predetermined temperatures are well known and widely used. Typically, the containers include an insulating wall that surrounds the item and an insulated lid, which fits in a sealing arrangement onto the container to maintain an internal container temperature. The insulating wall may be constructed of solid foam like insulator such as polymeric foam or the wall may contain an evacuated airspace such as that found in Thermos flasks. Also, for keeping foodstuff chilled in an ice chest, for example, for use on a picnic, ice packs are available which must first be frozen before adding to the insulated container along with the foodstuff. This relatively simple method does, however, suffer from a number of significant disadvantages. Most of the insulating materials used serve only as thermal insulators and do not have any significant heat capacity. As such, they are inefficient at maintaining the internal temperature of the container for a prolonged period of time. Furthermore, some containers can either accumulate or retain heat, but are not transportable as such. These usually fit within a larger container, or include their own power system to control the temperature therein. Also, for applications such as a freezer or a kitchen stove or the like, the insulating walls do not accumulate or retain the heat to minimize the heat transfer with the environment.
Thus, there is a need for an insulator for use with a container which is self-contained and which insulates pre heated or pre-cooled items for an extended period of time.
The inventor has unexpectedly discovered that an aqueous mixture of silicone-gel material, when sandwiched between two sealed walls, forms an insulator, which if it surrounds an item having a predetermined temperature, maintains the item at the predetermined temperature for a significant period of time (up to many hours for a cold item). Advantageously, a container that includes the insulator has significantly improved insulating properties and when pre-cooled or pre-heated, maintains an internal storage temperature for an extended period of time. Foodstuff that is pre-heated or pre-cooled can be stored for extended periods in the container and the container will maintain the internal temperature for the extended period. Other applications include, but are not limited to, the use of the container for transporting human organs for transplant or for transporting other perishable medical specimens. Desirably, the material can be used to increase the energy efficiency of appliances such as refrigerators or stoves, ovens, freezers and water tanks, by insulating the outer shell with the material. One may also contemplate the use of this material in the building trade to provide effective insulation in the walls"" cavities. Advantageously, the silicone-gel mixture is an inert, non-toxic, biodegradable, and non-adhesive aqueous silicone-gel that also has heat/cold accumulating properties otherwise known as Phase Change Material (PCM), which minimizes heat exchange from the container to the surrounding environment.
According to a first aspect of the present invention, there is provided a self-contained insulated container for maintaining an item at a predetermined temperature, the container having an inner sidewall and an outer sidewall, the sidewalls being spaced apart from each other and closed off to define an insulating chamber therebetween, the container comprises:
a storage area for receiving the item therein, the storage area being defined by the inner sidewall, the storage area being at a first storage temperature;
the insulating chamber being substantially filled with a first insulating material, the first insulating material being an aqueous silicone-gel mixture, the first insulating material being at a first insulating temperature, the storage area attaining a second storage temperature after the item is placed therein, the first insulating material maintaining the second storage temperature and the item at the predetermined temperature for a storage period.
In one embodiment, the first insulating material is located centrally in the insulating chamber, the first insulating material having first and second air spaces on each side of the first insulating material, the first air space being adjacent the inner sidewall and second air space being adjacent the outer sidewall.
Typically, first and second sectional walls are located between the first insulating material and the first and second air spaces.
Typically, a second insulating material is located on either side of the first and second air spaces, the second insulating material being respectively adjacent the inner sidewall and the outer sidewall.
In one embodiment, the container is a generally closable container and defines side panels, a floor panel, and an openable lid panel, at least one of the side, floor and lid panels including the insulating chamber.
According to a second aspect of the present invention, there is provided an insulator liner for use with a container having an inner sidewall and an outer sidewall, the sidewalls being closed off and defining an insulating chamber therebetween, the container being for storing a pre-heated or a pre-cooled item, the insulator liner comprises:
an insulating material, the insulating material being made from an aqueous silicone-gel mixture, the material substantially filling the insulating chamber, the insulating material being at a first insulating temperature; and
a storage area defined by the inner sidewall being at a first storage temperature, the storage area attaining a second storage temperature after the item is placed therein, the insulating material maintaining the second storage temperature and the item at a pre-cooled or a pre-heated temperature for a storage period.
According to a third aspect of the present invention, there is provided a method of maintaining the second storage temperature and the predetermined temperature of a pre-cooled item for an extended storage period in the self-contained insulated container as described hereinabove, the method comprises:
insulating the pre-cooled item in the container, the container being pre-cooled to attain the first insulating temperature and the first storage temperature, the storage area attaining the second storage temperature after the pre-cooled item is placed therein, so as to maintain, for the storage period, the second storage temperature and the pre-cooled item at the pre-determined temperature.